Diseño de una red de transporte de datos implementado MPLS, utilizando el simulador GNS 3 para la interconexión de sitios remotos con su sitio central a través de redes privadas virtuales(VPN)

El trabajo lo realizamos sobre el Sistema Operativo Ubunto con una simulación aplicada en el programa GNS3 (Simulador grafico de redes) elegido por sus propiedades gráficas y capacidad para soportar el IOS (Internetwork Operating System) real de los router, gracias a las bases que tiene en Dynamips, PEMU (incluyendo el encapsulador) y en parte en Dynagen. GNS 3 también utiliza la tecnología SVG para proveer símbolos de alta calidad para la realización de los mágicos diseños de topologías de red. La tecnología MPLS se basa en el análisis del envío de paquetes de una red, usando conmutación de etiquetas, lo cual es la base principal de este protocolo, el manejo que MPLS da a las redes privadas virtuales (VPNs) para la interconexión de sitios remotos con sus sitios centrales al adoptar una VPN MPLS será capaz de reducir complejidad en la administración de la red, aminorar los costos, mejorando el desempeño de la red y obteniendo conectividad universal. La red privada virtual (VPN) es una tecnología de red que permite la extención de una red privada sobre una red de uso pública como lo es el internet. Las VPN basadas en MPLS superan la mayor parte de los inconvenientes de las otras tecnologías de VPN. MPLS opera entre la capa de enlace de datos (capa 2) y la capa de red (capa 3) del modelo OSI, juntando ambas capas y haciendo uso de la velocidad del envío (forwarding) y del control del enrutador (routing), de esta forma logramos la creación de nuestra topología con redes flexibles y escalables, es decir que gracias a este conjunto de herramientas y sus características logramos con éxito nuestra meta

Arabidopsis DEMETER-LIKE proteins DML2 and DML3 are required for appropriate distribution of DNA methylation marks

Cytosine DNA methylation is a stable epigenetic mark for maintenance of gene silencing across cellular divisions, but it is a reversible modification. Genetic and biochemical studies have revealed that the Arabidopsis DNA glycosylase domain-containing proteins ROS1 (REPRESSOR OF SILENCING 1) and DME (DEMETER) initiate erasure of 5-methylcytosine through a base excision repair process. The Arabidopsis genome encodes two paralogs of ROS1 and DME, referred to as DEMETER-LIKE proteins DML2 and DML3. We have found that DML2 and DML3 are 5-methylcytosine DNA glycosylases that are expressed ina wi de range of plant organs. We analyzed the distribution of methylation marks at two methylated loci in wild-type and dmlmu tant plants. Mutations in DML2 and/or DML3 lead to hypermethylation of cytosine residues that are unmethylated or weakly methylated in wild-type plants. In contrast, sites that are heavily methylated in wild-type plants are hypomethylated in mutants. These results suggest that DML2 and DML3 are required not only for removing DNA methylation marks from improperly-methylated cytosines, but also for maintenance of high methylation levels in properly targeted sites

Dissolved CH4 coupled to photosynthetic picoeukaryotes in oxic waters and to cumulative chlorophyll a in anoxic waters of reservoirs

Methane (CH4) emissions from reservoirs are responsible for most of the atmospheric climatic forcing of these aquatic ecosystems, comparable to emissions from paddies or biomass burning. Primarily, CH4 is produced during the anaerobic mineralization of organic carbon in anoxic sediments by methanogenic archaea. However, the origin of the recurrent and ubiquitous CH4 supersaturation in oxic waters (i.e., the methane paradox) is still controversial. Here, we determined the dissolved CH4 concentration in the water column of 12 reservoirs during summer stratification and winter mixing to explore CH4 sources in oxic waters. Reservoir sizes ranged from 1.18 to 26.13 km(2). We found that dissolved CH4 in the water column varied by up to 4 orders of magnitude (0.02-213.64 mu mol L-1), and all oxic depths were consistently supersaturated in both periods. Phytoplanktonic sources appear to determine the concentration of CH4 in these reservoirs primarily. In anoxic waters, the depth-cumulative chlorophyll a concentration, a proxy for the phytoplanktonic biomass exported to sediments, was correlated to CH4 concentration. In oxic waters, the photosynthetic picoeukaryotes' abundance was significantly correlated to the dissolved CH4 concentration during both the stratification and the mixing. The mean depth of the reservoirs, as a surrogate of the vertical CH4 transport from sediment to the oxic waters, also contributed notably to the CH4 concentration in oxic waters. Our findings suggest that photosynthetic picoeukaryotes can play a significant role in determining CH4 concentration in oxic waters, although their role as CH4 sources to explain the methane paradox has been poorly explored

Physical Exercise and Fitness Level Are Related to Cognitive and Psychosocial Functioning in Adolescents

The purpose of this study was to analyze the relationships among physical exercise and fitness with selective attention, concentration, processing speed, general self-efficacy, self-rated health, and satisfaction with life. 208 adolescents between 14 and 16 years, from the city of Malaga (Spain), participated in the study. A comparative and predictive design was used to carry out this research. The instruments used for the evaluation were the Tanita R BC-601 Body Composition Monitor, the Eurofit Physical Condition Test Battery, the D2 Test of Attention, the WISC-IV Symbol Search and Coding tests, the General Self-Efficacy Scale (GSE), the General Health Questionnaire (GHQ-28), and the Satisfaction with Life Scale (SWLS). Analysis of variance (ANOVA), Kruskal–Wallis test, correlation analysis and linear regression were used to contrast the research objectives. The results indicated that adolescents who practiced more hours of physical exercise per week and were in better physical fitness achieved higher scores in selective attention, concentration, processing speed, general self-efficacy, self-rated health, and satisfaction with life. In addition, cardiorespiratory fitness was the physical fitness variable most closely related to and predictive of cognitive and psychosocial functioning. Cardiorespiratory fitness was predictor of all the variables analyzed, except the factor anxiety and insomnia (self-rated health), and life satisfaction that were predicted by horizontal jump measurements and fat mass, respectively. Thus, the study findings indicate that adolescents who practiced more weekly physical exercise and had a higher level of physical fitness scored better on the cognitive functioning and psychosocial tests evaluated. The data suggest that engaging in physical exercise and fitness in adolescence may be appropriate to improve health and well-being, contributing to better development at this stage

Regularizador híbrido para el registro a medida de imágenes médicas

Durante los últimos dos años, ha surgido un gran interés por encontrar nuevos términos de regularización que resulten especialmente adecuados para el registro de imágenes médicas. Los ejemplos más recientes en la literatura están basados en derivadas de primer y/o segundo orden. En este trabajo se propone un nuevo regularizador, basado en derivadas de orden fraccionario, para el registro de imágenes médicas. Puede considerarse como una generalización de los métodos de registro por difusión (derivadas de primer orden) y por curvatura (derivadas de segundo orden), pero con la estrategia propuesta es posible obtener mejores resultados en el registro final desde el punto de vista variacional (i.e., en términos tanto de similitud entre las imágenes como de suavidad en la transformación estimada), y en un menor número de iteraciones del algoritmo de registro.Ministerio de Ciencia y Tecnología a través del proyecto TEC2006-13338/TCM, y por la Agencia Regional de Ciencia y Tecnología (Fundación Séneca) a través del proyecto 03122/PI/05

Methylation-independent DNA Binding Modulates Specificity of Repressor of Silencing 1 (ROS1) and Facilitates Demethylation in Long Substrates

DNA cytosine methylation is an epigenetic mark that promotes gene silencing and performs critical roles during reproduction and development in both plants and animals. The genomic distribution of DNA methylation is the dynamic outcome of opposing methylation and demethylation processes. In plants, active demethylation occurs through a base excision repair pathway initiated by 5-methycytosine (5- meC) DNA glycosylases of the REPRESSOR OF SILENCING 1 (ROS1) / DEMETER (DME) family. To gain insight into the mechanism by which Arabidopsis ROS1 recognizes and excises 5-meC we have identified those protein regions that are required for efficient DNA binding and catalysis. We have found that a short aminoterminal lysine-rich domain conserved in members of the ROS1/DME family mediates strong methylation-independent binding of ROS1 to DNA, and is required for efficient activity on 5-meC:G, but not for T:G processing. Removal of this domain does not significantly affect 5-meC excision from short molecules, but strongly decreases ROS1 activity on long DNA substrates. This region is not required for product binding and is not involved in the distributive behavior of the enzyme on substrates containing multiple 5- meC residues. Altogether, our results suggest that methylation-independent DNA binding allows ROS1 to perform a highly redundant search for efficient excision of a nondamaged, correctly-paired base such as 5- meC in long stretches of DNA. These findings may have implications for understanding the evolution of structure and target specificity in DNA glycosylases

Registro variacional óptimo de imágenes médicas

La correcta selección de parámetros en los métodos de registro no paramétrico de imagen es un problema aún sin resolver. No hay acuerdo sobre cuáles son valores óptimos de estos parámetros, que dependen de las propias imágenes a registrar. Para abordar este problema, en este trabajo se propone un método que consta de dos pasos para obtener los parámetros que nos ofrecen desde un punto de vista variacional el compromiso óptimo entre la similitud de las imágenes registradas y la suavidad de la transformación resultante

Nuevas tendencias en redes neuronales artificiales: extreme learning machine

Las redes neuronales artificiales han sido ampliamente utilizadas para resolver problemas de diagnosis médica, reconocimiento de voz, predicción de índices bursatiles, etc. A pesar de ello, presentan como claros inconvenientes el elevado tiempo de cálculo necesario y la convergencia a mínimos locales. Este artículo analiza un novedoso, rápido y eficiente método para el entrenamiento de redes tipo “feed-forward” conocido como Extreme Learning Machine.Este trabajo está parcialmente financiado por el MEC a través del proyecto TEC2006-13338/TCM

Implementación eficiente de los métodos variacionales de registro de imagen

Los métodos de registro de imagen se clasifican habitualmente en dos grandes grupos: métodos paramétricos, donde los puntos de referencia (o landmarks) juegan un papel importante, y métodos no paramétricos, los cuales se basan en la minimización de una medida de distancia que se expresa mediante un sistema de ecuaciones en derivadas parciales (PDEs)Este trabajo ha sido parcialmente subvencionado por el Ministerio de Educación y Ciencia, a través del proyecto TEC2006-13338/TCM